(1) Field of the Invention
The present invention relates to ISDN (Integrated Services Digital Network) terminal equipment which can operate with either a circuit switching (circuit switched) communication system or a packet switching communication system.
For example, there are three types of G4 facsimile terminal equipment which can be connected to an ISDN network: the first type can carry out data communication by a circuit switching mode only, the second type can carry out data communication by a packet switching mode only, and the third type can carry out data communication by either the circuit switching mode (circuit mode) or the packet switching mode (packet mode). However, generally, a calling party does not know which type of G4 facsimile terminal equipment is connected to the ISDN network at a called party.
(2) Description of the Related Art
In conventional G4 facsimile terminal equipment which can carry out data communication by either the circuit switching mode or the packet switching mode, an operator must set manually the G4 facsimile terminal equipment to the circuit switching mode or the packet switching mode when starting data communication (sending facsimile data). When the operator does not know which type of G4 facsimile terminal equipment is connected to the ISDN network at a called party, the operator first tries data communication by one of the circuit switching mode and the packet switching mode. If the data communication cannot be carried out normally by that mode, the operator tries data communication again by using the other mode; where the setting and changing of the modes are carried out manually by the operator. Namely, bothersome manual operations are required for the operator of the calling party in the conventional G4 facsimile terminal equipment.